Electrical connection having radial crimp and axial indentation

ABSTRACT

Wire is connected to ferrule by radially crimping the ferrule onto the wire and, while the ferrule is held in the crimping device, axially indenting the wire and staking it against the internal wall of the ferrule.

United States Patent [1 Edwards, Sr. et al.

[ Apr. 2, 1974 154] ELECTRICAL CONNECTION HAVING RADIAL CRIMP AND AXIAL INDENTATION [75] Inventors: Joseph R. Edwards, Sr., Largo;

James Albert Kloth, St. Petersburg, both of Fla.

[73] Assignee: AMP Corporation, Harrisburg, Pa.

[22] Filed: Aug. 23, 1972 [21] Appl. No.: 283,142

[52] US. Cl. 72/410, 29/203 H [51] Int. Cl 821d 37/12 [58] Field of Search 72/409, 410, 403;

, 29/203 D, 203 H, 203 I -IC,203/HM, 203 HT, 282; 81/343 [56] References Cited UNITED STATES PATENTS 3,029,670 4/1962 Over et a1. 29/203 H 3,662,452 5/1972 Stoncstrum 29/282 2,377,829 6/1945 Vaill 3,252,316 5/1966 Haucke 72/410 Primary ExaminerCharles W. Lanham Assistant Examiner-Michael J. Keenan [57] ABSTRACT Wire is connected to ferrule by radially crimping the ferrule onto the wire and, while the ferrule is held in the crimping device, axially indenting the wire and staking it against the internal wall of the ferrule.

6 Claims, 10 Drawing Figures PATENTEDAPR 2 i974 SHEET 2 BF 5 CRIMP AND AXIAL INDENTATION BACKGROUND OF THE INVENTION This invention relates to crimped electrical connec-' tions of the type in. which a ferrule is crimped onto a wire. The invention is primarily directed to the'problem of connecting terminals to aluminum wires and the disclosed embodiment is particularly intended for aluminum wires. However, it will be apparent that the principles of the invention can be used for other wire-ferrule combinations.

It is commonpractice to electrically and mechanically connect a terminal member to a wire by simply crimping the ferrule portion of the connector onto the wireby means of suitable crimping dies. Most'crimped connections involvecopper wires and terminals which are of copper or copper alloys. Where the terminal and the connector are of copper or copper alloy, the crimping operation is carried out by radially compressing the terminal ferrule onto the wire and .good results are. obtained if prudent and sound engineering practice is followed. and if the known principles for crimping are observed.

The crimping of electrical connecting devices onto aluminum wires is not so straightforward a process as the crimping of terminals onto copper wires and crimping practice which suffices for copper Wires is not generally applicable to aluminum wires. The problems encountered in the crimping of terminals onto aluminum wires arise in part from the fact that aluminum ordinarily has an extremely thin oxide coating thereon which must be fractured durin'g'the crimping operation and which will reform aftercompletion of the crimping operation to the detriment of the electrical connection. Problems also arise from the galvanic corrosion effects which result if the wire is of aluminum and the terminal is of some other metal. Previously suggested solutions to the probleni'of crimping terminals onto aluminum wires have required the use of viscous greases and metal particles in the terminal or have required special platings on the terminal and/or liners in the terminal barrel which are designed to cause radial flow of the aluminum wire into the liners.

detail below, and which is shown in the accompanying drawing inwhich:

FIG. 1 is a perspective view of a preferred form of crimping tool in accordance with the invention.

FIG. 2 is a perspective view of a crimped connection in accordance with the invention.

FIG. 3-is a' sectional side view of a terminal of the type used to form crimped connections as shown in FIG. 2. 'v j FIG. 4 is a fragmentary sectional view illustrating the formation of a crimped-connection in accordance with the invention, thisview showing the'wire and terminal after the terminalhas been radially crimped and'prior to axial staking or'indentation of the wire.

FIG. 5 is a view similar to FIG. 4 but showing the axial indentation operation.

FIGS. 9 and 10 are perspective views of composite strip stock metal which can be used in the manufacture of terminals intended for the practice of the invention.

These prior art proposed solutions are satisfactory trical connection between a wireand a ferrule in combination with a. mechanical connection such that the electrical connection is not subject to mechanical abuse. A still further object'is to provide an improved method of crimping a terminal device onto a wire and an improved apparatus for carrying out terminal crimping operations.

These and other objects of the invention are achieved in a preferred embodiment thereof which is briefly described in the foregoing abstract, which is described in Referring first to FIG. 3, the invention is directed to the formation of a crimped connection between a terminal'4 and a wire having strands 6 and an insulating covering 8. The terminal has a tubular ferrule portion 10 and a projecting tongue 12, the ferrule being adapted to receive the stripped end of the wire. A cylindrical sleeve 14 is mounted on the ferrule and extends rearwardly therefrom as shown at 1 5. The portion of the sleeve adjacent to the righthandend of the ferrule is inwardly folded and inclined to provide a conical surface ,which serves to guide the stripped end of the wirev into the ferrule. The righthand end of the sleeve is reversely bent as shown'at 18 so that the entrance to the portion 15 is slightly constricted. The ferrule l0'may be of copper or other relatively soft and ductile metal and the sleeve 14, which is relatively thin as compared to the ferrule, maybe of steel. The sleeve gives addedstrength to'the connection and functions as a support for the insulation of the wire as will become apparent as this description proceeds. A tubular sheath of suitable plastic 20 is provided in surrounding areas tothe sleeve to insulate the finished connection.

In accordance with known crimping practice, the wire is inserted into the terminal until the stripped end is located in the ferrule 10 and the end portion of the insulation is disposed in the sleeve 15. The ferrule and the sleeve are radially crimped onto the wire. In accordance with the present invention, the wire is connected to the ferrule by a separate indenting or staking operation which will now be described.

The detailsof a crimped connection in accordance with the present invention can be best understood from v 'a'description of the tool 22 for forming the connection v in the manner in which the tool is operated. The crimping tool 22 (FIG. I) has a frame 24 from which a fixed handle 26 extends. A movable handle 28 is pivotally mounted in the frame at 30 and cam or toggle means (not specifically shown) are provided in the-frame for driving a ram upwardly when the handles are closed.

One suitable cam type mechanism for a tool of the general type shown is shown in US. Pat. No. 3,029,670.

The frame has an integral head 32 having fixed crimping dies 34, 36 and a fixed confining die 35 mounted therein in side-by-side relationship. Movable crimping dies 38, 40 and a movable confining die 41 are mounted on the upper end of the tool ram so that a terminal positioned between the dies will be crimped when the handles 26, 28 are closed. As illustrated in FIG. 4 the dies 34, 38 function to crimp the righthand portion of the terminal onto the insulation 8 of the wire and the dies 36, 40 crimp the ferrule portion of the terminal onto the stripped end of the wire.

As is apparent from FIGS. 4 and 5, the confining dies '35, 41 are relatively more thin than the crimping dies and are located such that their opposed surfaces 37, 39 are against, and in confining relationship to, the end of ferrule portion of the terminal. These confining dies are dimensioned such that when the tool handles are closed, the surfaces 37, 39 are against the surface ofthe insulating sheath 20 but they did not, in moving to their closed positions (shown in FIGS. 4 and indent or deform the ferrule portion of the terminal, to any substantial extent. As will be explained hereinbelow, these confining dies function to confine the ferrule while it is being axially indented.

The tool 22 is also provided with an indenting or axial staking device 42, FIG. 7 comprising a cylindrical barrel 44having an integral flange 46 which is secured to the tool head by fasteners 48. The barrel 44 is axially bored at 52 and is counter-bored as shown at 50 to an enlarged diameter. It will be apparent from FIG. 7 that the axis of the bore is in alignment with the axis ofa terminal positioned at crimping dies. It will be noted also that the barrel 44 is cut away on its under side adjacent to the tool head for the accomodations of the tongue of the terminal.

An indenting tool mounted in the bore 52 has a shank portion 56 and a generally conical end 58 that penetrates the wire strands as explained below. Shank 56 extends rightwardly and merges with a cylindrical slide 60 contained in the counterbore. This slide is resiliently biased rightwardly as viewed in the drawing by a coil spring 61 which is interposed between the end of the counter-bore and the face of the slide. The righthand end of the slide has an inclined surface 62 which bears against a complementary inclined surface of a cam 64. This cam has a reduced diameter shank 66 that extends through a cap nut 68 which is threaded onto the right hand end of the barrel. The cam 64 is locked in position by a lock nut 70 as shown.

A handle 72 extends radially from the slide 60 and through an opening in the wall of the counter-bored portion of the barrel. The arrangement is such that if the handle is rotated from the full line position of FIG. 7 to the dotted line position, the slide 60 and the indenting tool 58, 56 will move leftwardly from the position of FIG. 4 to the position of FIG. 5.

When a terminal is to be crimped onto a wire, the terminal barrel is positioned between the crimping dies as shown in FIG. 7 with the terminal tongue located against the surface 54. The movable tool handle 28 is then moved toward the fixed handle to raise the lower crimping dies until the terminal is gripped between the dies. This initial manipulation of the handles is not carried to completion; the terminal is not crimped at this stage but the wire end is then inserted into the terminal.

Thereafter the handles are moved to their fully closed position as shown in FIG. 4 and the terminal is crimped onto the conducting core of the wire and onto the insulation.

As is clearly shown in FIG. 4 the ferrule 10 is compressed onto the stripped end of the wire and the wire strands are substantially deformed and compressed in the constricted zone 74. However, the strands are not highly deformed at the lefthand end of the terminal.

While the handles are held in their closed positions and the terminal is gripped tightly in the crimping dies 34, 36, 38 and 40, the handle 72 is swung from the full line position of FIG. 7 to the dotted line position and the staking or indenting tool moves. leftwardly to the dotted line position of FIG. 7. During this movement of the indenting tool, it is rotated about its own axis through an angle of about The conical head of this tool moves into the bundle of wire strands and forms the conical indentation 76 shown in FIG. 6. The tips of the strands are severely cold worked by the tool and are pressed outwardly relative to the axis ofthe terminal and against the internal wall-0f the ferrule. The degree of flattening of the strands is greatest at the end of the wire and decreases along the length of the wire to the inner end of the depression or indentation 76. During this indenting and staking operation the end of the ferrule is confined against radial movement by the surfaces 37, 39 of the confining dies 35, 41. As a result of this axial indentation while the ferrule is confined, the ends of the wires are smeared against the external surface of the ferrule, the smearing being brought about by the extreme pressure of the indenting tool against the wire strands.

In the finished crimped connection the end portions of the strands present the appearance of a fused mass of metal from which the strands extend. In fact, the individual strands may not be capable of being identified by the unaided eye although metallographic examination will reveal lines of demarcation between the severely cold worked and deformed wire strands.

It is probable that some cold welding of the strands to each other and of the strands to the wall of the ferrule takes place although it is extremely difficult to positively determine the presence of cold welding. In any event, extremely good electrical characteristics are obtained and the intimacy of the contact between the strands and the ferrule prevents, or at least retards, minute separation (as might take place during temperature cycling) which permits corrosion and results in the deterioration of the connection.

As explained above, the electrical contact obtained at the end of the wire is protected from disturbance by the fact that the ferrule is crimped tightly onto the wire at 74. Since the ferrule is maintained under compression by the crimping dies 36, 40 while the wire is being indented at 76, the mechanical effects of the indentation do not affect the wire crimp 74.

Both solid and stranded aluminum wires have been terminated successfully by the practice of the invention. The invention is particularly effective in overcoming the problems encountered in terminating stranded aluminum wires of high strand count such as 19 strand and 41 strand aluminum wires.

The ferrule 10 will ordinarily be of relatively soft metal, particularly copper or aluminum. If copper, the ferrule may be coated with a metal which will suppress or retard galvanic corrosion effects. For example, copper terminals have been plated with tin and crimped and staked onto wire ends in accordance with the invention and have been found to be satisfactory.

Referring to FIG. 9, the ferrule portion and tongue portion 12 of the terminal may be manufactured from composite stock-metal if desired, the strip stock of FIG. 9 comprising a relatively wide strip 82 of copper and a narrow strip 84 of aluminum, the width of the strip 84 being such that the ferrule 10 of the connecting device will have an aluminum liner therein. FIG. 10 shows strip stock comprising copper 86 and a narrow aluminum inlay 88 whichmay also be used for the manufacture of the terminal. The strip stock metals of FIGS. 9 and 10 can be manufactured by bonding the aluminum to the copper and are particularly useful under circumstances where the termination is subjected to moist and saline environment.

It is to be understood that the term aluminum as used herein is intended to refer to aluminum alloys having a high percentage of'aluminums which are being used in the electrical arts for wire and for terminals, for example EC alloy, ASTM, specification B3l4-60.

The terminal shown in FIGS. 2 and 3 is of the conventional closed barrel type, which is to say that the channel portion is a continuous cylinder having no seam or having a welded or brazed seam. The principles of the invention are also applicable to open U-type terminals as shown'in FIG. 8. In this embodiment the terminal has a base or bight portion 79 having one pair of sidewalls 80 which are curled towards each other and into surrounding relationship with the stripped end of the wire, these sidewalls being offset along the length of the terminal and having overlapping ends as shown. A second pair of sidewalls 78 are crimped onto the insulation of the wire as previously described with reference to the embodiment of FIG. 2. Open U-type terminals require crimping dies which are different from the dies shown in the drawing, but inother respects the tooling performing the connection of FlG. 8 may be substantially similar to that required for the embodiment of FIG. 2.

It is to be understood that the crimping apparatus may be in the form ofa semi-automatic or an automatic bench mounted machine rather than a hand tool as described herein.-

Changes in construction will occur to those skilled in the art and various apparently'different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only.

We claim:

1. Apparatus for electrically and mechanically connecting a wire to an electrical connecting device, said connecting device having a ferrule portion which is adapted to receive an end of said wire, said apparatus comprising:

frame means,

die means in said frame means, said die means being movable along a predetermined path between open and closed positions to crimp the ferrule-portion of a connectingdevice onto a wire positioned in said ferrule-portion,

a wire indenting tool on said frame means, said wire indenting tool comprising an indenting shaft oriented with its axis extending transversely of said predetermined path, said shaft having a tapered end located adjacent to said die means when said die means are in said closed position,

first actuating means for moving said die means from said open position to saidv closed positioned to crimp said ferrule portion onto said wire,

second actuating means for moving said indenting shaft axially into said ferrule and for rotating said shaft during said axial movement whereby,

upon movement of said die means to said closed position, said ferrule portion is crimped onto said wire, and upon axial movement of said shaft into said ferrule and accompanying formation of a generally tapered indentation in said wire, the end of said wire is drastically cold worked against the internal wall of said ferrule, the degree of cold working decreasing with the distance from the end of said wire.

2. Apparatus for electrically and mechanicallyconnecting a wire to an electrical connecting device, said connecting device having a ferrule portion which is adapted to receive an end of said wire, said apparatus comprising:

frame means, v

at least one pair of cooperable crimping dies in said A frame means, said dies being movable relatively towards and away from each other along a first predetermined path between opened and closed positions to'crimp the ferrule-portion of a connecting device onto a wire positioned in said ferrule portion,

a pair of cooperable confining dies, said confining dies being beside said crimping dies and being effective, when closed, to confine one end of said ferrule portion against radial expansion,

a wire indenting tool on said frame means, said wire indenting tool comprising an indenting shaft oriented with its axis extending transversely of said predetermined path, said shaft having a tapered end located adjacent to said dies when said dies are in said closed position,

first actuating means for moving said crimping and confining dies from said open position to said closed position to crimp said ferrule portion onto said wire,

second actuating means for moving said indenting shaft axially into said ferrule and for rotating said shaft during said axial movement whereby,

upon movement of said dies towards each other, said ferrule portion is inwardly crimped onto said wire, and upon axial movement of said shaft into said ferrule and accompanying rotation of said shaft, theend portion of said wire is spirally deformed inwardly along its axis, with accompanying formation of a generally tapered indentation in said wire, the end of said wire being drastically cold worked against the internal wall of said ferrule and the degree of cold working decreasing with the distance from the end of said wire.

3. Apparatus as set forth in claim 2, said apparatus having a second pair of cooperable crimping dies, said one pair of crimping dies being adapted to crimp portions of said ferrule onto the conducting core of an in- I sulated wire, said second pair of crimping dies being with said indenting tool and being effective to move said tool axially towards said die upon rotation of said indenting tool, and said second actuating means further comprising an indenting tool handle extending from said indenting tool to permit manual rotation of said indenting tool. 

1. Apparatus for electrically and mechanically connecting a wire to an electrical connecting device, said connecting device having a ferrule portion which is adapted to receive an end of said wire, said apparatus comprising: frame means, die means in said frame means, said die means being movable along a predetermined path between open and closed positions to crimp the ferrule-portion of a connecting device onto a wire positioned in said ferrule-portion, a wire indenting tool on said frame means, said wire indenting tool comprising an indenting shaft oriented with its axis extending transversely of said predetermined path, said shaft having a tapered end located adjacent to said die means when said die means are in said closed position, first actuating means for moving said die means from said open position to said closed positioned to crimp said ferrule portion onto said wire, second actuating means for moving said indenting shaft axially into said ferrule and for rotating said shaft during said axial movement whereby, upon movement of said die means to said closed position, said ferrule portion is crimped onto said wire, and upon axial movement of said shaft into said ferrule and accompanying formation of a generally tapered indentation in said wire, the end of said wire is drastically cold worked against the internal wall of said ferrule, the degree of cold working decreasing with the distance from the end of said wire.
 2. Apparatus for electrically and mechanically connecting a wire to an electrical connecting device, said connecting device having a ferrule portion which is adapted to receive an end of said wire, said apparatus comprising: frame means, at least one pair of cooperable crimping dies in said frame means, said dies being movable relatively towards and away from each other along a first predetermined path between opened and closed positions to crimp the ferrule-portion of a connecting device onto a wire positioned in said ferrule portion, a pair of cooperable confining dies, said confining dies being beside said crimping dies and being effective, when closed, to confine one end of said ferrule portion against radial expansion, a wire indenting tool on said frame means, said wire indenting tool comprising an indenting shaft oriented with its axis extending transversely of said predetermined path, said shaft having a tapered end located adjacent to said dies when said dies are in said closed position, first actuating means for moving said crimping and confining dies from said open position to said closed position to crimp said ferrule portion onto said wire, second actuating means for moving said indenting shaft axially into said ferrule and for rotating said shaft during said axial movement whereby, upon movement of said dies towards each other, said ferrule portion is inwardly crimped onto said wire, and upon axial movement of said shaft into said ferrule and accompanying rotation of said shaft, the end portion of said wire is spirally deformed inwardly along its axis, with accompanying formation of a generally tapered indentation in said wire, the end of said wire being drastically cold worked against the internal wall of said ferrule and the degree of cold working decreasing with the distance from the end of said wire.
 3. Apparatus as set forth in claim 2, said apparatus having a second pair of cooperable crimping dies, said one pair of crimping dies being adapted to crimp portions of said ferrule onto the conducting core of an insulated wire, said second pair of crimping dies being adapted to crimp an insulating covering on said ferrule onto the insulation of said wire.
 4. Apparatus as set forth in claim 2, said apparatus comprising a hand tool, said first actuating means comprising closable handles and means in said frame responsive to said closable handles for moving said dies from said open position to said closed position.
 5. A hand tool as set forth in claim 4 including a cylindrical barrel on said frame, said indenting tool being in said barrel.
 6. A hand tool as set forth in claim 5 wherein said second actuating means comprises camming means in said barrel, said camming means being in engagement with said indenting tool and being effective to move said tool axially towards said die upon rotation of said indenting tool, and said second actuating means further comprising an indenting tool handle extending from said indenting tool to permit manual rotation of said indenting tool. 